As a material for a battery case for lithium ion secondary batteries, etc., a packaging material of a multilayered structure is used, in which resin layers are laminated on both surfaces of a metal foil via an adhesion layer.
In manufacturing the packaging material, as a method of bonding the metal foil and the resin layer, a dry laminating method is employed, in which using a two-part curing type adhesive agent made of polyol and isocyanate, after applying the adhesive agent and evaporating the solvent, the metal foil and the resin layer are bonded. In the dry laminating method, after bonding the metal foil and the resin layer, aging is performed at about several tens ° C. for several days to facilitate the curing of the adhesive agent to thereby enhance the adhesive strength (see Patent Documents 1 to 6).
Further, when manufacturing a case using the aforementioned sheet-like packaging material, for the purpose of securing an inner volume of the case, generally, the material is formed into a three-dimensional shape by drawing or bulging.